Membrane switch

ABSTRACT

The present invention is directed to an improved membrane switch of the kind comprising a polymeric overlay, which is generally planar and containing designated switch areas thereon for manual operation by pressure. The switch is formed from several layers of conductive and nonconductive materials. Specifically, the switch includes a pair of electronic switch circuit leads disposed in noncontacting proximity. A substantially planar circuit completing layer formed to correspond with the pair of switch circuit leads is formed from conductive material and disposed and spaced array substantially parallel to the switch circuit leads. A nonconductive spacer is disposed, in one preferred embodiment, between the electric circuit and the circuit completing layer, with the spacer having a plurality of apertures therein of a selected density sufficient to provide a selected touch pressure. In another preferred embodiment, the substantially planar circuit completing layer is omitted, and the pair of electronic switch circuit leads are instead disposed in separate planes and are separated by the spacer, such that manual pressure on the switch will contact one circuit lead with the other circuit lead through the apertures in the spacer.

BACKGROUND OF THE INVENTION

The present invention relates generally to switches, and moreparticularly to an improved membrance switch.

In the prior art, various types of membrane switches have been utilizedon machinery panels, calculators, computers, etc. Such membrane switcheshave the advantage over other forms of switches that they present asubstantially flat upper surface, and are relatively very thin ascompared with mechanical switches. Also, such membrane switches areenclosed, and contain very few moving parts. Accordingly, such membraneswitches have had exceeding long useful lives.

One difficulty with prior art membrane switches has been the inabilityto control selevtively the amount of pressure necessary to operate thistype of switch. Also, another difficulty with prior art switches hasbeen frequently the necessity for switches requiring different manualpressures on the same or different switch panels. Also, the priorswitches have had the further difficulty of an inability to providedifferent operating pressures within the same switch.

Thus, in view of the difficulties and deficiencies with prior artmembrane switches, it is an object of the improved membrane switch ofthe present application to materially alleviate such difficulties anddeficiencies.

SUMMARY OF THE INVENTION

The improved membrane switch of the present invention concerns switcheshaving a top sheet with portions designated thereon for manual pushingto operate the switch.

The improved membrane switch of the present invention comprises a pairof electronic switch circuit leads which are disposed in noncontactingand mutually relative proximity. A substantially planar circuitcompleting means, the size and shape corresponding with at least aportion of the electronic switch circuit leads, is formed from aconductive material and is disposed in spaced array and substantiallyparallel to the switch circuits.

A spacer means of a nonconductive material is disposed between the pairof electronic circuit leads and the circuit completing means. The spacermeans has a plurality of apertures therein of a selected densitysufficient to provide a selected touch pressure for pushing portions ofthe circuit completing means which appear through apertures in thespacer into contact with portions of the pair of electronic switchcircuit leads to complete the circuit and to operate the switch.

In an alternative preferred embodiment, the electronic switch circuitleads are disposed in separate planes and substantially parallel to eachother and are separated by the spacer means. In such embodiment, theelectronic circuit leads are disposed opposite each other, such thatsufficient manual pressure on the switch disposes the electronic switchleads into contact with each other through the apertures in the spacermeans to operate the swtich. In this embodiment also, the density andlocation of the apertures controls the amount of pressure necessary tooperate the switch.

In both of the above embodiments, the manual pressure necessary tooperate the switch may be varied in switches on the same switch panel,or even in portions of the same discrete membrane switch, by varying thesize and density of the apertures in the spacer means.

The improved membrane switch of the present invention will be betterunderstood with reference to the following brief description of thedrawing, detailed description of preferred embodiments, the appendedclaims, and the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING

Preferred embodiments of the improved membrane switch apparatus of thepresent invention are set forth in the accompanying drawing, and inwhich:

FIG. 1 is a perspective view of an exemplary membrane switch panelsetting forth discrete areas containing visual indicia for designatingand defining portions of the panel to receive manual pressure foroperating an electronic improved membrane switch disposed therebeneath;

FIG. 2 is a greatly enlarged, fragmented view of the improved membraneswitch of the present invention, shown in peeled-apart array, andillustrating the intertwining, but noncontacting, electronic switchcircuit leads, and the facing nonconductive, grid-like spacer meansdisposed atop the substantially planar circuit completing means formedfrom a conductive material;

FIG. 3 is a greatly enlarged top view of the improved membrane switch ofthe present invention, with layers of the electronic panel cut away toillustrate the disposition of circuit completing means, and spacer means(in phantom) disposed atop the pair of electronic switch circuit leads;

FIG. 4 is an even further enlarged, fragmented side view taken alonglines 4--4 of FIG. 3, and illustrating the various layers comprising theimproved membrane switch of the present invention;

FIG. 5 is the view of the present invention as shown in FIG. 4 showingmanual pressure being applied thereto operate the switch;

FIG. 6 is an enlarged fragmentary view of an alternative preferredembodiment of the improved membrane switch of the present inventionillustrating the electronic switch circuit leads being disposed inseparate planes, with the grid-like spacer means of nonconductivematerial disposed therebetween, such that manual pressure on the switchwill contact one electronic lead with the other, and through theapertures in the grid of the spacer means to operate this switch;

FIG. 7 is a greatly enlarged, and fragmented side view of thealternative preferred embodiment of the improved membrane switch of FIG.6; and

FIG. 8 is a greatly enlarged, and fragmentary top view of the spacermeans layer of the improved membrane switch of the present inventionillustrating different densities of the grid-like spacer means, whichcan be utilized in different individual switches, or which may beutilized in different portions of the same switch.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The improved membrane switch of the present invention has a top sheetwith portions designated by visual indicia thereon for manual pushing tooperate the switch. The improved membrane switch of the presentinvention includes a pair of electronic switch circuit leads which aredisposed in noncontacting, and mutually relative proximity. Asubstantially planar circuit completing means has a size and shape tocorrespond with at least a portion of the pair of switch circuit leads.Such circuit completing means is formed from a conductive material, andis disposed in spaced array and substantially parallel to the switchcircuits. A spacer means of a nonconductive material is disposed betweenthe pair or electronic circuit leads and the circuit completing means.The spacer means has a plurality of apertures therein of a selecteddensity sufficient to provide a selective touch pressure for pushingportions of the circuit completing means appearing through the aperturesand the spacer into contact with portions of the pair of electronicswitch circuit leads to complete the circuit and to operate the switch.

The improved membrane switch of the present invention also may includeas and for the spacer means a grid formed from lines of a nonconductivematerial. Such nonconductive material preferably comprises anonconductive paint, which is disposed on the circuit completing means.Such circuit completing means preferably comprises a conductive paintmaterial, and such conductive paint material is preferably disposed upona backing sheet.

The nonconductive spacer apertures may be selected to varying densityand different portions of the nonconductive spacer, to provide avariable touch pressure at different portions of the nonconductivespacer. The pair of electronic switch circuit leads is preferablydisposed in a common plane in preferred embodiments.

In other preferred embodiments, the pair of electronic switch circuitleads are disposed in separate planes, and are disposed substantiallyparallel to each other and are separated by the spacer means. In thispreferred alternative embodiment, the electronic switch circuit leadsare disposed opposite each other, whereby sufficient manual pressure onthe switch disposes the electronic switch leads into contact through theapertures in the spacer means to operate the switch.

In either of the above embodiments of the improved membrane switch ofthe present invention, the electronic switch circuits may be preferablyformed by printing. Also, the top sheet as for the switch panelcomprises a nonconductive polymeric overlay containing visual indiciathereon to define the switch area to be operated by manual pressure.

Referring now to the drawing and to FIG. 1 in particular, the improvedmembrane switch of the present invention generally 10 is containedwithin a switch panel 11 has a top sheet 12 with switch portions 14designated by visual indicia thereon for manual pushing to operate theswitch 10. Such switch panel 11 may have an electronic connecting meansin the form preferably of a flexible tail 16.

As shown in FIGS. 2-5, the improved membrane switch 10 of the presentinvention includes a pair of electronic switch circuit leads 18, 20which are disposed in noncontacting, and mutually relative proximity.Such switch leads 18, 20 are disposed onto a polymeric sheet 21, whichis in turn secured preferably by a contact adhesive 22 to top sheet 12,which contains the visual indicia.

A substantially planar circuit completing means 24 has a size and shapeto correspond with at least a portion of the pair of switch circuitleads 18, 20. Such circuit completing means 24 is formed from aconductive material, and is disposed in spaced array and substantiallyparallel to the switch circuit leads 18, 20, as shown in FIGS. 4-5. Thecircuit completing means 24 is disposed on a polymeric sheet 25, whichis backed by adhesive 27, which in turn is protected by a peel strip 29until applied for use to a control panel, etc.

A spacer means 26 of a nonconductive material is disposed between thepair of electronic circuit leads 18, 20, and the circuit completingmeans 24. Such spacer means 26 may also preferably include anonconductive border portion 28. The spacer means 26 has a plurality ofapertures 30 therein of a selected density sufficient to provide aselective touch pressure for pushing portions of the circuit completingmeans 24 appearing through the apertures 30 of the spacer means 26 intocontact with portions of the pair of electronic switch circuit leads 18,20 to complete the circuit and to operate switch 10, as shown in FIG. 5by manual digit 32 lines shown in phantom.

The improved membrane switch of the present invention 10 mayspecifically include as and for the spacer means 26 the grid formed fromlines of a nonconductive material, as shown in the Figures hereof. Ofcourse, spacer means 26 may take shapes and forms other than a grid.Such nonconductive material for spacer means 26 preferably comprises anonconductive paint, which is disposed on the circuit completing means.Such circuit completing means preferably comprises a conductive paintmaterial.

The apertures 30 in spacer means 26 may be selected to have varyingdensity and to be disposed in different portions of the nonconductivespacer means 26, to provide a variable touch pressure at differentportions of the nonconductive spacer means 26, as shown for example inFIG. 8. Therein, spacer means generally 26 contains in left-hand portionrelatively fewer grid lines 26a for lower pressure actuation, the middleportion contains a medium number of grid lines 26b for moderate pressureactuation, and the right-hand portion contains a dense number of gridlines 26c for high pressure actuation.

In other preferred embodiments as shown in FIGS. 6-7, generally asswitch 110 the electronic switch circuit leads 118, 120 are disposed inseparate planes, are disposed substantially parallel to each other andare separated by the spacer means 126. The remaining elements of switch110 are analogous to those of the first embodiment, switch 10, of FIGS.2-5, and like elements are designated with like numerals plus 100. Inthe preferred alternative embodiment of 110, the electronic switchcircuit leads 118, 120 are disposed opposite each other and preferablyat 90° to each other, whereby sufficient manual pressure on the switchdisposes the electronic switch leads 118, 120 into contact through theapertures 130 in spacer means 126 to operate the switch 110.

In the above description, specific details of an embodiment of theinvention have been provided for a thorough understanding of theinvention concepts. It will be understood by those skilled in the artthat many of these details may be varied without departing from thespirit and scope of the invention.

What is claimed is:
 1. An improved membrane switch having a top sheetwith a portion designated thereon for manual pushing to operate theswitch, said switch comprising:a pair of electronic switch circuit leadsdisposed in the same plane in noncontacting mutually relative closeproximity, said pair of electronic switch circuit leads each comprisinga plurality of intertwined but non-contacting elongated bars, said barshaving a designated width; supporting means for said electronic switchcircuit leads; a substantially planar circuit completing means of a sizeand shape to correspond with at least a portion of said pair of switchcircuit leads, formed from conductive material, and disposed in spacedarray and substantially parallel to said switch circuit leads; and anonconductive spacer means comprising a grid, said grid comprising aplurality of substantially intersecting lines of a nonconductivematerial, said substantially intersecting lines of said grid having awidth which is substantially narrow relative to the selected width ofsaid elongated bars of said electronic switch circuit leads, saidsubstantially intersecting lines of said grid disposed directly betweensaid pair of electronic circuit leads and said circuit completing means,said spacer means grid having a plurality of apertures therein formed bysaid substantially intersecting lines of said grid and having a selectedgrid density sufficient to provide a selected touch pressure duringpushing at least a portion of the said circuit completing meansappearing through the apertures in said spacer grid into contact with atleast a portion of the pair of electronic switch circuit leads tocomplete the circuit and to operate the switch.
 2. The improved membraneswitch of claim 1 wherein said nonconductive material comprises anonconductive paint.
 3. The improved membrane switch of claim 1 whereinsaid circuit completing means comprises a conductive paint material. 4.The improved membrane switch of claim 3 wherein said conductive paintmaterial is disposed upon a backing sheet.
 5. The improved membraneswitch of claim 1 wherein said circuit completing means is disposed upona backing sheet.
 6. The improved membrane switch of claim 1 wherein saidnonconductive spacer apertures vary in density in different portions ofsaid nonconductive spacer to provide a variable touch pressure atdifferent portions of said nonconductive spacer.
 7. The improvedmembrane switch of claim 1 wherein said pair of electronic switchcircuit leads are disposed in a common plane.
 8. The improved membraneswitch of claim 1 wherein said electronic switch circuit leads areprinted of conductive paint.
 9. The improved membrane switch of claim 1wherein the top sheet comprises a nonconductive polymeric overlaycontaining visual indicia thereon to define the switch portion to beoperated by manual pushing.
 10. The improved membrane switch of claim 1wherein said supporting means for said electronic switch circuit leadscomprises a substantially planar polymeric sheet.
 11. The improvedmembrane switch of claim 1 wherein said intertwined elongated bars ofsaid electronic switch circuit leads combine to cover a defined areawhich is substantially co-extensive with a portion designated on the topsheet for manual pushing to operate the switch.